Technical Abstract:
Environmental determinants of protein and oil composition of the soybean [Glycine max (L.) Merr.] seed were determined by comparing monthly temperature variables of the growing seasons to protein and oil data for the years 1959 to 1996 from three locations listed in the Uniform Soybean Tests, Northern Region. Classification and regression 'tree-based' analysis were conducted to determine the month, environmental variable, and 'splitting' points that correctly classified most of the 186 location-years regarding below versus above median protein and oil concentration. The protein concentrations were separated by temperature variables from the months of April and August. The oil concentrations were classified by temperature variables from the months of August and September. Total protein and oil concentrations were separated by August and July temperature variables. These data demonstrate that tree-based models can utilize monthly temperature variables of the crop year and relate them to the protein and oil concentration in the seed. These results could be used by the processing industry to estimate seed composition before harvest and by plant breeders to enhance total seed protein and oil concentration by selecting for genotypes that are maximally responsive to the specific months.